Hey awaken, I'm in the same boat as you. I have the corsair 400cx and I'm looking to order the GTX 460 1GB. Could you reply here if you had success with it? Based on what I have read, it shouldn't be a problem. Thanks.
Sorry for the delay in the update. I installed the Gigabyte 460 1GB version. I also measured power at the wall using a Kill A Watt. The PSU handled the new card with no issues. My power draw at the wall is around 275W when playing SCII on Ultra.
If you have the 400CX, you'll be fine.